Index: vm_mmap.c
===================================================================
RCS file: /home/cvsup/freebsd/CVS/src/sys/vm/vm_mmap.c,v
retrieving revision 1.53.2.3
retrieving revision 1.53.2.4
diff -u -r1.53.2.3 -r1.53.2.4
--- vm_mmap.c	1998/03/12 19:36:50	1.53.2.3
+++ vm_mmap.c	1998/05/24 19:47:02	1.53.2.4
@@ -57,6 +57,7 @@
 #include <sys/file.h>
 #include <sys/mman.h>
 #include <sys/conf.h>
+#include <sys/stat.h>
 #include <sys/vmmeter.h>
 
 #include <miscfs/specfs/specdev.h>
@@ -275,12 +276,26 @@
 			 * we're at securelevel < 1, to allow the XIG X server
 			 * to continue to work.
 			 */
-			if (((flags & MAP_SHARED) != 0 ||
-				(vp->v_type == VCHR && disablexworkaround)) &&
-				(fp->f_flag & FWRITE) == 0 && (prot & PROT_WRITE) != 0)
-				return (EACCES);
-			else
+
+			if ((flags & MAP_SHARED) != 0 ||
+			    (vp->v_type == VCHR && disablexworkaround)) {
+				if ((fp->f_flag & FWRITE) != 0) {
+					struct vattr va;
+
+					if ((error =
+					    VOP_GETATTR(vp, &va,
+						        p->p_ucred, p)))
+						return (error);
+					if ((va.va_flags &
+					    (IMMUTABLE|APPEND)) == 0)
+						maxprot |= VM_PROT_WRITE;
+					else if (prot & PROT_WRITE)
+						return (EPERM);
+				} else if ((prot & PROT_WRITE) != 0)
+					return (EACCES);
+			} else
 				maxprot |= VM_PROT_WRITE;
+
 			handle = (caddr_t) vp;
 		}
 	}